X-ray tube.



. KESSELRING.

X-RAYTUBB.

APPLICATION FILED OCT. 17. 1912.

Patented Apr. 7, 1914 E il, rrr il HERMANN 1VI. KESSELRING, OF CHICAGO,ILLINOIS.

X-RAY TUBE.

' Specification of Letters Patent.

Patented Apr. 7, 1914.

Application filed October 17, 1912. Serial No. 726,230.

l of whichthe following is a specication.

In the use of X-ray tubes, as hitherto constructed, theyfrequentlypuncture at points adjacent to the electrodes, and moreespecially at or near the junction of the body and handle portions atthe cathode side of the tube. The primary cause of this puncturing isthat the surfaceportions of the metal electrode become oxidized andmetal oXid particles are deposited upon the sur- `face of the glass.When a particle of metal loXid lodges upon the glass at a point near thecathode, more especially, the current is apt to jump from the cathode tosuch parti` cle causing a spark which punctures the glass at that pointand destroys the usefulness of the tube.

. My object is so to improve the construc- `tion of X-ray tubes as toobviate or, at least, greatly diminish the said danger.

It is further my object to provide means for the rapid withdrawal ofheat from the body of the tube, to prevent overheating thereof and thusrender it easier to handle with less liability of injury to the tube.

The accompanying drawing is a sectional view of an X-ray tube, of known'construction, provided with my improvements.

The tube is of glass having the usual spherical body-portion 1, and thehollow eX- tensions 2, 3 forming handles. In the eXtension 2 is acathode 4 formed with a head, having a concave face 5, and a stem 6.

The numeral 7 designates the target which serves likewise as the mainanode of the tube. The stem 8 of the anodeis in the eX- tension 3. Onthe body-portion is the usual regulator 9 and also a hollow extension10, containing an assistant anode 11.

Supported in the part 2 is an insulating shield 12, preferably oflead-glass. The shield 12 surrounds the stem and head of the cathodeleaving only the concave face 5 thereof exposed. The shield 12 is out ofcontact With the stem 6 of the cathode eX- cept at the point 13 where itis contracted about the same to steady it. The shield 12, being oflead-glass, by which I mean glass having a material percentage of leadin its composition, is impervious to cathode rays and operates as acurrent insulator serving to confine the discharge of current to theconcave face 5, and squarely against the target 7, thereby limitingdissemination of the cathode rays in the tube. The shield 12 also servesas a heat-insulator for the cathode which protects the extension 2 andadj acent body-portion 1 from the heat generated at the cathode.

The anode or target 7 is a solid cylindrical metal block with aninclined face containing a platinum disk 14. Surrounding the target is ametal sleeve 15 having an opening 16 through which the X-rays areprojected.

Within and integral with the extension 3 is a preferably lead-glassshield formed with an inner-tubular portion 17 loosely surrounding thestem 8 and attached by the metal sleeve or ferrule 18 to the cylindricalhead 7. Integral with the inner sleeve 17 is an outer lead-glass sleeveor tube 19 surrounding the parts 17, 18 and 15, and eX- tending slightlybeyond the latter. It has an opening 20 registering with the opening-16. The inner and outer sleeves or tubes 17, 19, serve as current andheat-insulators for the head and stem of the anode and protect thesurrounding extension 3 and adjacent body-portion 1 from the heat of theanode. The outer-end portion ofthe eXtension 3 is enlarged into a bulb22, and is of thinner glass than the body-portion of the tube. The glassbeing thinner permits heat to discharge or radiate therefrom morerapidly, and in practice much of the heat genlerated at the anode isconducted, along the parts 7, 8, 18, 17 and 19 to the thin glass bulb 22whence it radiates rapidly into the surrounding atmosphere. The bulb 22,in practice, serves in factto withdraw much of the .heat from the mainbulb, or body-portion, 1 and thus diminish danger of injury to the tubein the handling thereof.

The assistant anode 11 is loosely surrounded, in the part or extension10 of the tube by a, preferably lead-glass, tube, or shield, 21,integral with the part 10 and serving as a current and heat-insulator.

While the tube is in operation the cathode 4, more especially, becomesheated to a high temperature and the main purpose of the shield 12 is toreduce the heat radiated therefrom to the extension 2 and adjacentbodyportion 1 of the tube. It has been found in practice that if thelatter become heated to a high temperature 'they are very apt tofracture if touched with metal or any comparatively cold object.Furthermore, heating, particularly, of the extension 2, interferes withthe handling of the tube by the operator. The shield 12 absorbs much ofthe heat radiated from lthe cathode and thus serves to prevent thesurrounding tube from being heated to a degree which will cause it tofracture and puncture, if touched with metal, as by a ring onr theoperators finger, and also prevents the extension 2 from being heatedlto a temperature which Willinterfere with ready handling thereof by theoperator. The inner and outer tubes or shields 17, 19 serve to insulatethe target or anode and to protect the surrounding parts 3 and 1 of thetube from theheat thereof. The shields 17, 19, furthermore, serve toprevent metal oxid loosened from the anode from being deposited againstadjacent parts j the inner surface of the handle or body-portion nearenough to the cathode for the current to spark, across. This s arkingagainst' the glass of the handle or bo y-portlon is apt to, andfrequently does, result in puncturing the lass thereby destroying theusefulness of t e tube. When the particles of metal oxid remain in theshield .12, the current may jump thereto and cause sparks, but as .theshield is very hot and not exposed to the chilling effect of theoutside. atmosphere, it is not liable to puncture, though if it didpuncture, it would Anot destroy the usefulness of the tube. Incidentallythe leadv lass shields described reduce danger of -ray burns thehandling of the implement.

The foregoing description is intended to convey a clear understandin ofmy improvements in what I nonT believe to be the best form of theirembodiment, and-no undue limitation should be understood therefrom. Itis my intention to claim all that is novel in my invention, andthat theclaims shall be construed as broadly as the prior state of the art mayWarrant.

What I claim as new and desire to secure by Letters Patent is 1. lIn anX-ray tube, the combination with the glass body-portion and electrodes,of a glass extension containing one of the electrodes and formed alongits outer-end portion with a compartment of thinner glass than the saidbody-portion, for the purpose set forth.

2. In an X-ray tube, the combination vvitl.` the glass body-portion andelectrodes, of a glass extension having an enlarged outerend portionforming a compartment of thinner glass than the said body-portion, forthe purpose set forth. A

HERMANN M. KESSELRING.

L. I-IEIsLAR, J. LANDEsMAN.

